J . Med. Chem. 1992,35, 4713-4719
4713
Synthesis and Antiviral Activity of Deoxy Analogs of I-[ (2-Hydroxyethoxy)methyl]-6-(phenylthio)thymine(HEPT) as Potent and Selective Anti-HIV-1 Agents’ Hiromichi Tanaka,’?? Hideaki Takashima: Maaaru Ubasawa: Kouichi Sekiya: Issei Nitta,t Masanori Baba,t Shiro Shigeta,l Richard T. Walker,ll Erik De Clercq,l and Tadashi Miyasakat School of Pharmaceutical Science, Showa University, Hatanodai 1-5-8, Shinagawa-ku, Tokyo 142, Japan, Mitsubishi Kasei Corporation Research Center, Yokohama 227, Japan, Fukushima Medical College, Fukushima 960-12, Japan, School of Chemistry, University of Birmingham, Birmingham B15 2TT, United Kingdom, and Rega Institute for Medical Research, Katholieke Uniuersiteit Leuven, B-3000 Leuven, Belgium Received July 20, 1992
The effect of substitution in the acyclic structure of 1-[(2-hydroxyethoxy)methyl]-6-(phenylthio)thymine (HEPT) on anti-HIV-1activity was investigated by synthesizing a series of deoxy analogs and related compounds. Preparation of 1-[(2-alkyloxyethoxy)methyll-6-(phenylthio)thymine(24)derivatives was carried out based on alkylation of HEPT with primary alkyl halides. Preparation of the 1-[(alkyloxy)methyll-6-(phenylthio)thymine (26-31)and l-[(alkyloxy)methyl]-6-(arylthio)2-thiouracil (32-45) derivatives was carried out on the basis of LDA lithiation of l-[(alkyloxy)methyl] thymine (9-14)and 1-[(alkyloxy)methyll-2-thiouracil(15-25) followed by reaction with diary1disulfides. The oxidative hydrolysis of the 2-thiouracilderivatives gave 1-[(akyloxy)methyl]6-(arylthio)uracil derivatives (46-57). l-Alkyl-6-(phenylthio)thymine(59-61) derivatives were prepared on the basis of alkylation of 6-(phenylthio)thymine (58). Methylation of the hydroxyl group of HEPT did not affect the anti-HIV-1 activity of HEPT. Substitution of the 142hydroxyeth0xy)methylgroup by ethyl, butyl, methoxymethyl, (propyloxy)methyl, and (butyloxy)methyl groups somewhat improved the original anti-HIV-1 activity of HEPT. Substitution with ethoxymethyl and (benzy1oxy)methyl groups further potentiated the activity [ECw: l-(ethoxymethyl)-6-(phenylthio)thymine (27),0.33pM; 1-[(benzyloxy)methyl]-6-(pheny1thio)thymine(31), 0.088 pM1. When the 5-methyl group of 27 and 31 was replaced by an ethyl or an isopropyl group, the anti-HIV-1activity was improved remarkably [ECw: 5-ethyl-l-(ethoxymethyl)-6-(phenylthio)uracil (46),0.019 pM; 5-ethyl-l-[(benzyloxy)methyl]-6-(phenylthio)uracil(52),0.0059 pM; 5430propyl-l-(ethoxymethyl)-6-(phenylthio)uracil(55), 0.012 p M 5-isopropyl-l- [(benzyloxy)methyl]6-(phenylthio)uracil(56), 0.0027 pM1. Introduction of two m-methyl groups into the phenylthio ring also potentiated the activity. Human immunodeficiency virus type 1(HIV-l)2*3 is the causative agent of acquired immunodeficiency syndrome (AIDS), which is characterized as a systemic and fatal disorder. 3‘-Azido-3‘-deoxythymidine(AZT)is a thymidine analog that suppresses HIV-1 replication and is currently a licensed compound available for the treatment of patients w i t h AIDS.4r5 Despite its clinical efficacy,longterm adminiatration of AZT often leads to toxic side effects, ~~
t Showa University.
t Mitsubishi Kasei Corp.
Fukushima Medical College. Birmingham. 1 Rega Institute. (1)Part of this work has appeared in a preliminary communication: Tanaka, H.; Baba, M.; Saito, S.; Miyasaka, T.; Takashima, H.; Sekiya, K.; Ubasawa, M.; Nitta, I.; Walker, R. T.; Nakashima, H.; De Clercq, E. Specific Anti-HIV-1 “Acyclonucleosides” Which Cannot Be Phosphorylated: Synthesis of Some Deoxy Analogues of l-1(2-Hydroxyethory)methyl]-6-(phenylthio)thymine. J.Med. Chem. 1991,34,160& 1611. (2)Barr&Sinoussi, F.; Chermann, J. C.; Rey, F.; Nugeyre, M. T.; Chamaret, 5.; Gmest, J.; Dauguet, C.; Mer-Bli, C.; VBzinet-Brun, F.; Rouzioux, C.; Rozenbaum, W.; Montagnier, L. Isolation of a T-lymphotropic Retrovirue from a Patient at Risk for Acquired Immune Deficiency Syndrome (AIDS). Science (Wwhington, D.C.)1983,220,868-871. (3)Gallo,R. C.; Salahuddin,S. 2.;Popovic, M.; Shearer,G. M.; Kaplan, M.; Haynes, B.F.;Palker,T. J.;Redfeild,R.; Oleske,J.; Safai,B.;Whita, G.; Foeter, P.; Markham, P. D. Frequent Detection and Isolation of Cytopathic Retroviruses (HTLV-111) from Patients with AIDS and at Risk for AIDS. Science (Washington, D.C.)1984,224, 600-503. f
I University of
such as bone marrow suppression.6 A purine dideoxynucleoside,2’,3’-dideoxyinosine (DDI),’ has recently been approved as an alternative drug for the patients who do not tolerate AZT,yet it also has unfavorable side effects! AZT and DDI act as inhibitorsof viral reverse transcriptase (4) Mitsuya, H.; Weinhold, K. J.; Furman, P. A.; St. Clair, M. H.; Nusinoff-Lehrman, S.; Gallo, R. C.; Bologneai, D.; Barry, D. W.; Broder, S. 3’-Azido-3’-deoxythymidine (BW A509U): An Antiviral Agent That Inhibits the Infectivity and Cytopathic Effect of Human T-lymphotropic Virus Type IWlymphadenopathy-associated V i In Vitro. hoc. Natl. Acad. Sci. U.S.A. 1986,82, 7096-7100. (6)Fischl, M. A.; Richman, D. D.; Grieco, M. H.; Gottlieb, M. 5.; Volberding, P. A.; Laskin, 0.L.; Leedom,J. M.; Groopman,J. E.; Mildvan, D.; Schooley, R. T.; Jackson, G. G.; Durack, D. T.; King, D.; the AZT Collaborative Working Group. The Efficacy of Azidothymidine (AZT) in the Treatment of Patients with AIDS and AIDS-related Complex: A Double-blind,Placebo-controlledTrial. N. Engl. J.Med. 1987,317,185191. (6) Richman, D. D.; Fischl, M. A,; Grieco, M. H.; Gottlieb, M. S.; Volberding, P. A.; Laskin, 0.L.; Leedom,J. M.; Groopman,J. E.; Mildvan, D.; Hirsch, M. S.; Jackson, G. G.; Durack, D. T.; Nusinoff-Lehnnan,8.; the AZT CollaborativeWorkingGroup. The Toxicity of Azidothymidine (AZT) in the Reatment of Patients with AIDS and AIDS-related Complex: A Double-blind, placebo-controlled Trial. N.Engl. J. Med. 1987,317, 192-197. (7) Mitsuya, H.; Broder, S. Inhibition of the in vitro Infectivity and Cytopathic Effect of Human T-lymphotrophic V i m Type nulymphadenopathy-aeeociatedVirus (HTLV-IIULAV)by 2’,3’-Dideoxynucleoaides. Roc. Natl. Acad. Sci. U.S.A. 1986,83,1911-1916. (8)Yarchoan, R.; Mitauya, H.; Thomas, R. V.; Pluda, J. M.; Hartman, N. R.; Perno, C.-F.; Marczyk, K. S.; Allain,J.-P.; Johns, D. G.; Broder, 5.In Vivo Activity Against HIV and Favorable Toxicity Profile of 2’3’Dideoxyinoeine. Science (Washington, D.C.)1989,246,412-415.
0022-262319211835-4713$03.00/0 @ 1992 American Chemical Society
4714 Journal of Medicinal Chemistry, 1992, Vol. 35, No. 25
Tanaka et al.
Scheme I 0
0
i ) siiylating agent H
9-25
5-8
0
32-39, 4 2 - 4 5
H202-NaOH
5, 9-14,26-31 X = 0, R" = Me 6, 15-22, 32-42 X = S, R' = Et 7, 23-24,43-44 X = S,R" = Pr-i 8, 25, 45 X = S,R" = Pr-c R"' = Me,Et, Pr, Bu, CHZPh, etc. Y = H, 3,5di-Me, or 3,5-di-CI (see Table Iand Table II)
R"'
46-54 R" = Et 55-56 R" = Pr-i 57 R' = Pr-c
after being phosphorylated to their 5'-triphosphates?Jo Such 5'-triphosphates may also interact with the host dellular DNA polymerases.ll This nonspecific action appears to contribute to the toxic side effects of this class of compounds. Therefore, it is still necessary to find new compounds having low toxicity and, preferably,a different mode of inhibition of viral replication. We have previously reported that l-[(2-hydroxyethoxy)methyl] -6-(pheny1thio)thymine(I; HEPT) had potent and 0
1; HEPT
selectivein vitro activity against HIV-1.12 It is interesting that HEPT does not inhibit the replication of animal retrovirus or even HIV-2.13 HEPT can be regarded as an acyclonucleoside analog, yet its triphosphate does not interact with HIV-1 reverse transcriptase.12 In addition, HEPT does not compete with [3H-methyllthymidine for phosphorylation by thymidine kinase derived from MT-4 cells.13 We recently found that HEPT itself proved inhibitory to recombinant HIV-1 reverse trans~riptase.'~ These results prompted us to synthesize HEPT analogs which cannot be phosphorylated. In the present article, we report the synthesis and anti-HIV-1activity of deoxy HEPT analogs. The structureactivity relationships of these compounds are also described. Chemistry Initially, preparation of 0-alkyl derivatives of HEPT was carried out. Selective 0-alkylation of HEPT was accomplished by using 1.0 equiv of alkyl halides, such as MeI, pentyl iodide, and benzyl bromide, in the presence of 2.1 equiv of NaH in THF at room temperature to give 2-4 in 87 %I, 21%I, and 80 %I yields, respectively. 0
2 R=Me 3 R = CSH,,-n 4 R = CH2Ph
We have already reported that the lithiation approach is highly efficient for synthesizing6-substitutedpyrimidine acyclonucleosides.12J~17 As shown in Scheme I, a series of analogs lacking a hydroxyl function in the acyclic structure of HEPT was synthesized from the corresponding pyrimidine bases (5-8) by employing the lithiation strategy as a key reaction step. The preparation of 1-[(alkyloxy)methyllthyminee and 5-alkyl-l-[(alkyloxy)methylluracils, used as substrates for the lithiation, deserves some comment. When thymine (5) was treated with N,O-bis(trimethylsily1)acetamide (9) Furman,P.A.;Fyfe,J.A.;St.Clair,M.H.;Weinhold,K. J.;Rideout, J. L.; Freeman, G. A.;Nusinoff-Lehrman, S.; Bolognesi, D. P.; Broder, S.; Mitsuya, H.; Barry, D. W. Phosphorylation of 3'-Azido-3'-deoxythymidine and Selective Interaction of the 5'-Triphosphate with Human Immunodeficiency Virus Reverse Transcriptase. hoc. Natl. Acad. Sci. U.S.A. 1986,83,8333-8337. (10) St. C h i , M. H.; Richards, C. A.; Spector, T.; Weinhold, K. J.; Miller, W. H.; Langlois,A. J.; Furman, P. A. 3'-Azido-3'-deoxythymidine Triphosphate as an Inhibitor and Substrate of Purified Human I"unodeficiency V i Reverse Transcriptase. Anitmicrob. Agents Chemother. 1987,31, 1972-1977. (11)KBning, H.; Behr, E.; Uwer, J.; Kurth, R. Azidothymidine Triphosphate Is an Inhibitor of Both Human Immunodeficiency Virus Type 1ReverseTranacriptaseandDNAPolymeraseGamma. Anitmicrob. Agents Chemother. 1989,33,2109-2114. (12) Miyasaka, T.; Tanaka, H.; Baba, M.; Hayakawa, H.; Walker, R. T.; Balzarini, J.; De Clercq, E. A Novel Lead for Specific Anti-HIV-1 Agents: 1-[(2-Hydroxyethoxy)methyll-6-(phenylthio)thymine.J.Med. Chem. 1989,32, 2507-2509. (13)Baba, M.; Tanaka, H.; De Clercq, E.; Pauwels, R.; Balzarini, J.; Schols, D.; Nakashima, H.; Pemo, C.-F.; Walker, R. T.; Miyasaka, T. Highly SpecificInhibition of Human ImmunodeficiencyV i m Type 1by a Novel6-Substituted AcyclouridineDerivative. Biochem.Biophys. Res. Common. 1989,165, 1375-1381. (14) Baba, M.; De Clercq, E.; Tanaka, H.; Ubasawa, M.; Takashima, H.; Sekiya, K.; Nitta, I.; Umezu, K.; Nakashima, H.; Mori, S.; Shigeta, S.; Walker, R. T.; Miyasaka, T. Potent and SelectiveInhibition of Human Immunodeficiency Virus Type 1(HIV-1) by 5-Ethy1-6-phenylthiouracil Derivatives Through Their Interaction with the HIV-1 Reverse Transcriptase. R o c . Natl. Acad. Sci. U.S.A. 1991,88, 2356-2360. (15) Tanaka, H.; Baba, M.; Hayakawa, H.; SakamaJci, T.; Miyasaka, T.;Ubasawa,M.;Takashima,H.;Sekiya,K.;Nitta,I.;Shigeta,S.; Walker, R. T.; Balzarini, J.; De Clercq, E. A New Clam of HIV-1-Specific 6-Substituted Acyclouridine derivatives: Synthesis and Anti-HIV-1 Activity of 5-or 6-Substituted Analogues of 1-[(2-Hydroxyethoxy)methyI]6-(phenylthio)thymine (HEPT). J.Med. Chem. 1991, 34, 349-357. (16) Tanaka, H.; Baba, M.; Ubasawa, M.; Takashima, H.; Sekiya, K.; Nitta, I.; Shigeta, S.; Walker, R. T.; De Clercq,E.; Miyasaka, T. Synthesis and Anti-HIV-1 Activity of 2-, 3-, and 4-Substituted Analogues of 1-[(2Hydroxyethoxy)methyl]-6-(phenylthio)thpine(HEFT). J.Med. Chem. 1991,34, 1394-1399. (17) Tanaka, H.; Takashima, H.; Ubasawa, M.; Sekiya, K.; Nitta, I.; Baba, M.; Shigeta,S.; Walker,R. T.; De Clercq, E.; Miy&,T. Structureactivity Relationshipa of 1-[(2-Hydroxyethoxy)methyll-&(phenylthio)thymine (HEPT) Analogues: Effect of Substitutions at the C-6 Phenyl Ring and at the C-5 position on Anti-HIV-1 activity. J. Med. Chem. 1992,35,337-345.
Synthesis and Antiviral Activity of HEPT Analogs
Journal of Medicinal Chemistry, 1992, Vol. 35, No.25 4715
(BSA;2.2 equiv) in CHzCl2 at room temperature followed by reaction with the alkyl chloromethyl ether (1.2 equiv) in the presence of B u N I (0.1 equiv) under reflux, the 1-[(alkyloxy)methyllthymines (9-14) were obtained in good yield.l* In contrast, similar treatment of 5-alkyl-2thiouracils (6-8)19 gave the corresponding products in uniformly low yield.20 The yields were slightly improved by applying an alternative method published by Kim and co-workers.21 Thus, when compounds 6-8 were silylated with 1,1,1,3,3,3-hexamethyldisilazanein the presence of a catalytic amount of (NH&S04 at refluxing temperature and then reacted with the alkyl chloromethyl ether (1.2 equiv) in the presence of CsI (1equiv), compounds 15-25 were obtained in 16-43% yield. The C-6 position of compounds 9-25 was lithiated with LDA (lithium diisopropylamide,2.2 equiv) in THF below -70 "C for 1h and the resulting lithiated species was then allowed to react with the diary1disulfide (1.5 equiv).This reaction gave the desired 6-(phenylthio)thymine deriva(32tives (26-31) and 5-alkyl-6-(arylthio)-2-thiouracils 45). The 5-alkyluracil analogs (46-57) were prepared from compounds 32-39 and 42-45 by oxidative hydrolysis (H202 in aqueous NaOH) of the thione function.22 To simplify further the acyclic structure of HEPT, analogs having a primary alkyl group at the N-1 position were also prepared. Acid hydrolysis of HEPT in concentrated aqueous HC1-MeOH at 80 "C afforded 6-(pheny1thio)thymine(58) in 24% yield. This compound was
Scheme I1
H
N
L
58 R ' = H 59 R'=Me 60 R = E t 61 R = B u
allowed to react with Me1 (1.0 equiv) in the presence of K2C03 (1.0 equiv) to give a monomethylated (13%)and a dimethylated (34%) product after column chromatography on silica gel. When the monomethyl derivativewas subjected to a radical-mediated desulfurizative stannylation followed by protonolysisaccordingto the published method,231-methylthymine was obtained (Scheme II).24 This confiimed the monomethyl derivativeto be l-methyl6-(pheny1thio)thymine (59). Following this alkylation method, compounds 60 (10%) and 61 (18%)were also prepared. (18) Ogilvie, K. K.; Hamilton,H. G.; Gillen,M. F.;Radatus, K.; Smith, Galloway, K. S. Uracil Analogues of the Acyclo-nucleoside 9-[[2K. 0.; Hydroxy-1-(hydroxymethyl)ethoxylmethyllguanine(BIOLF-62). Can. J. Chem. 1984,62,16-21. (19) Basnak, I.; Frakas, J. Synthesis of Uracils Substituted in the Position 5 or 5,6 with Alkyl or Cycloalkyl Groups and Their UV Spectra. Cotlect. Czech. Chem. Commun. 1979,44,2426-2437. (20) For example,reaction of 5-ethyl-2-thiouracilwith BSA (2.2equiv) and the following reaction with chloromethylethylether (1.2 equiv) gave a complex mixture of products. After chromatographic purification, the was obtained in only 15% desired 1-(ethoxymethyl)-5-ethyl-2-thiouracil yield. (21) Kim, Y. H.; Kim, J. Y.; Lee, C. H. Efficient Synthesis of Acyclic Nucleosides by N-Alkylation of Pyrimidine and Purine-bases Using a New Coupling Agent of Cesium Iodide. Chem. Lett. 1988, 10461048. (22) Johnson, T. B.; Schroeder, E. F. Researches on Pyrimidines. CXXII. Improved Methods for the Synthesis of Orotic Acid. J. Am. Chem. SOC.1931,53,1989-1993. (23) Tanaka, H.; Hayakawa, H.; Obi, K.;Miyasaka,T. SyntheticRoute to 5-SubstitutedUridinesViaa New Type of DesulfurizativeStannylation. Tetrahedron 1986, 42, 4187-4195. (24) Wittenburg, E. Chem. Ber. 1966,99, 2391-2398.
59
Bu3SnH,AlBN
CF3COOH
*
SnBu,
Me
Me
AlBN 2,2'-azobisisobutyron1trile
Results of the Anti-HIV Assay and Discussion Anti-HIV-1 activity and cytotoxicityof HEPT analogs synthesizedin the present study are summarized in Table ID, together with those of HEPT and AZT. The procedure to measure anti-HIV-1 activity has been described prev i ~ u ~ l The y . ~HTLV-IIIB ~ strain of HIV-1and MT-4 cells were used for the assay. Among the 0-alkyl derivatives of HEPT, the 0-methyl derivative (2) retained the original activity of HEPT with a slight increase in cytotoxicity. This result suggested that, unlike acyclovir, HEPT did not require an hydroxy group in its acyclic structure. As can be seen from the data for compounds 3 and 4, the presence of a bulkier 0-alkyl group resulted in almost complete loss of the activity. Reflecting the above-mentioned positive result for compound 2, deoxy HEPT analogs 1-[(alkyloxy)methyll6-(phenylthio)thymines(26-31) showed a significant activity, except for compound 30 which had a [2-(trimethylsilyl)ethoxylmethy1group in the acyclic portion. It should be mentioned that a remarkable increase in antiHIV-1activity was accomplished at this stage, as is shown in the case of compound 27 (ECm = 0.33 pM),which corresponded to the genuine deoxy analog of HEPT, and for 1-[(benzyloxy)methyll-6-(phenylthio)thymine(31, ECw 0.088pM). In terms of SI value, the latter analog was now almost equivalent to AZT. Our previous studies concerning the structure-activity relationships of HEPT analogs suggested that the following modifications at the base moiety would potentiate its original activity: (1)Replacement of the 2-oxo function with a thione function.16 (2) Substitution at the meta position of the 6-phenylthio ring with two chlorine atoms or two methyl g r 0 u ~ s . l(3) ~ Replacement of the 5-methyl group with a bulkier alkyl g r 0 ~ p . lThe ~ molecular design of compounds 32-57 was based on these findings as well as the results from the present study of deoxy HEPT analogs. With respect to these compounds (32-571, again there was a general trend that a bulkier acyclic portion made the compound less active. To improve the ECm value, both ethoxymethyl and (benzy1oxy)methylgroups seemed to be the most suitable; further substitution uniformly increased the ECm value, as can be seen from the data of compounds 36-37 and 40-42. Compound 46, having an ethyl group at the C-5position, was 10 times more potent than its 5-methyl counterpart (27). The corresponding2-thio analog (32)had a similar ECm value as that of compound 46 but was much more cytotoxic. Although the above-mentioned meta substitution at the 6-phenylthio ring was certainly effective in improving activity, comparison of toxicity data for com(25) Pauwels, R.; De Clercq, E.; Desmyter, J.; Balzariii, J.; Goubau, P.;Herdewijn, P.;Vanderhaeghe,H.;Vandeputte, M. Sensitiveand Rapid Assay on MT-4 Cella for the Detection of Antiviral Compounds Againet the AIDS Virus J. Virol.Methods 1987,16,171-185.
4716 Journal of Medicinal Chemistry, 1992, Vol. 35, No.25
Tanaka et al.
Table I. Physical Properties of Compounds 9-25'
compd
X
9 10 11 12 13 14
0
RfTf
Rff
recrystn solv % yield mp, OC formula analysis Me Me EtOAc 54 142-143 C7HioNzOa C, H, N 0 Me Et i-PrOH-Et20 62 108-109 CdlZNZO3 C, H, N 0 Me Pr i-PrOH 63 141-142 C~irNzO3 C, H, N 0 Me BU i-PrOH 49 128-129 Ci~1Hi6N203 C, H, N 0 Me CH2CHzSiMes EtOAc-hexane 87 136-137 CliHzoNzO3Si C, H, N 0 Me CHzPh EtOAc-hexane 86 133-134 CisHififis C, H, N 15 S Et Et i-PrOH 37 111-112 CeHifizOzS C, H, N, S 16 S Et i-Pr i-PrOH 25 124-125 CioHi&OzS C, H, N, S 17 S Et c-Hex i-PrOH 34 123-124 CiaHdzOzS C, H, N, S 18 S Et Hex-c-CH2 i-PrOH 36 96-97 CirHnNzOzS C, H, N, S 19 S Et CHzPh i-PrOH 36 94 Cl4HldZOfi C, H, N, S 20 S Et CHzC&(4-Me) i-PrOH 23 110-111 C1EHleNZOZS C, H, N, S 21 S Et CH&6&(4-C1) i-PrOH 16 101-102 c14H16ClN202s C, H, N, S 22 S Et CHzCHzPh i-PrOH 32 129-130 Ci6Hi&OzS C, H, N, S 23 S i-Pr Et i-PrOH 31 93-94 c1oH1sNz02s C, H, N, S CHSh i-PrOH 24 S i-Pr 31 104-105 Ci&Ii&Ofi C, H, N, S 25 S C-Pr Et i-PrOH 43 123-124 CioHirNzOzS C, H, N, S a Other physical data (UV, mass spec, 'H NMR, and elemental analyses) of compounds 9-26 are presented in the supplementary material. ~~
~
Table 11. Physical Properties of Compounds 26-57" 0
compd
X
Rff
Me Me Me Me Me Me Et S Et S Et S Et S Et S Et S Et S Et S Et S Et S Et 8 i-Pr S i-Pr S c-Pr 0 Et 0 Et 0 Et 0 Et 0 Et 0 Et 0 Et 0 Et 0 Et 0 i-Pr 0 i-Pr 0 c-Pr a Other physical data 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 67
0 0 0 0 0 0 S
Rf?f
Y recrystn solv 5% yield mp, OC formula analysis EtOAc 73 148-150 Me EtOH Et 85 134 Pr EtOAc-hexane 77 136-138 Bu EtOAc-hexane 65 118-120 CHzCHzSiMes hexane 57 87-89 EtOH-H20 CHzPh 58 157-161 EtOAc-hexane Et 106-109 88 63 EtOAc-hexane Et 155-156 42 EtOAc-hexane Et 112-116 i-Pr EtOAc-hexane 63 141-142 EtOAc-hexane 71 c-Hex 139-141 EtOAc-hexane 72 CH2-c-Hex 134-135 CHzPh EtOH 89 151-153 CHzPh EtOAc-hexane 158-160 66 EtOAc-hexane 157-160 CHzCa(4-Me) 59 EtOAc-hexane 132-134 36 CHzC6&(4-C1) EtOAc-hexane 136138 32 CHzCHzPh EtOAc-hexane Et 138-140 70 EtOAc-hexane CHzPh 165-168 31 EtOAc-hexane Et 85 123-124 EtOAc-hexane 123-125 77 Et EtOAc-hexane 85 Et 165-166 EtOAc-hexane 56 159-162 Et i-Pr EtOAc-hexane 81 119-121 EtOAc-hexane c-Hex 79 167-171 EtOAc-hexane Hex-c-CHz 115-116 83 CHzPh H EtOAc-hexane 77 110-112 C&H&IiO& cl N; s 3,6-Mez EtOAchexane CHzPh 81 156158 CzzHuNzOaS*'/sHzO C, H,N,S CHzCHzPh H EtOAc-hexane 75 108-110 CziHzzNzOsS C, H, N, S Et H EtOAc-hexane 65 112-114 Ci&dsO~SJ/sH20 C, H, N,S CHzPh H EtOAc-hexane 66 138-141 C ~ ~ H Z Z N ~ O ~ S - ' / ~C, HH, Z ~N, S Et H EtOAc-hexane 91 94-97 Ci~Hi8Nz03S C, H, N, S (UV, Mass, lH NMR, and elemental analyses) of compounds 26-67 are presented in Supplementary Material.
pounds 33 and 34 and compounds47 and 48 clearly showed that analogs substituted with m-dimethylgroups provided much better SI values than those having m-dichloro substituents. The 5-isopropyl derivatives (43,44,55, and 56) were as potent as their 5-ethyl counterparts, yet introduction of the 5-cyclopropyl group (45 and 57) weakened the activity.
HI
6-(Phenylthio)thymine(58), the base moiety of HEPT, did not show any anti-HIV-1activity. Although l-methyl6-(phenylthio)thymine(6) was also inactive, introduction of an ethyl or butyl group into the N-1 position of compound 58 significantlycontributed to the anti-HIV-1 activity, as is shown by the ECsos of compounds 60 and 61. It could be assumed from this result that even the
Synthesis and Antiviral Activity of
Journal of Medicinal Chemistry, 1992, Vol. 36,No.25 4717
HEPT Analogs
Table 111. Inhibition of HIV-1 Recplication in MT-4 Cella by the Deoxy Analogs of HEPT 0
2 3 4 26 27 28 29 30 31
0 0 0 0 0 0 0 0 0
CI CI CI CI CI CI CI CI CI CI CI CI CI CI CI CI CI CI CI CI c1 c1 c1 c1 c1 c1 c1 c1 c1 c1 c1
2OCHzCHzOMe 20CHzCH2OCsHll-n zOCH2CH20CH2Ph 2OMe 2OEt 2OPr 2OBu zOCHaCH2SiMes 20CH2Ph 2OEt 2OEt 2OEt 2-i-Pr 20-c-Hex 2OCHrc-Hex 20CHSh 2OCHSh zOCHzC&(4-Me) 20CH2(4-C1) 2OCHaCHzPh 20Et 2OCHzPh 20Et 2OEt 2OEt 2OEt 20-i-Pr 20-c-Hex 2OCHz-c-Hex 2OCHzPh 2OCHzPh c1 zOCHzCH2Ph
Me Me Me Me Me Me Me Me Me Et Et Et Et Et Et Et Et Et Et Et i-Pr i-Pr c-Pr Et Et Et Et Et Et Et Et Et i-Pr i-Pr c-Pr Me Me Me Me Me
H H H H H H H H H H 3,5-M@ 3,5-c12 H H H H 3,6-Mez H H H H H H H 3,5-Me2 3,5-c12 H H H H 3,5-Me2 H
8.7 >55 2 20 2.1 0.33 3.6 4.7 >32 0.088 0.026 0.0061 0.013 0.22 1.6 0.35 0.0078 0.0069 0.078 0.012 0.091 0.014 0.0068 0.095 0.019 0.0054 0.0074 0.34 4.0 0.45 0.0059 0.0032 0.096 0.012 0.0027 0.1 >250 >150 2.2 1.2 7.0 0.003
299 55 45 244 231 147 83 32 95
34 455 139 >286 >12800 >2m >256 >1670 >220 >7140
81 32 S >load S 33 45 34 S >1ood S 35 223 S 36 >1ood S 37 >lood S 38 >2od S 39 >2od S 40 >2od 41 S >2od 42 S >lood S 43 >2940 >2od S 44 46 484 S 45 161 8600 46 0 >load >18500 47 0 45 6080 48 0 421 143 0 49 >1W >25 0 50 17 38 0 51 34 5800 0 52 >2od >6250 0 53 38 396 0 54 H 106 8830 0 55 H >2od >7410 CHzOCHnPh 0 56 H 224 2240 CH20Et 0 57
